Just stumbled across this site, and love it. Lots of great info here!
I just got my G5 iMac, and before purchasing it, I looked long and hard for 1GB RAM sticks to load it up with. I ended up getting 2 Rosewill sticks of 1GB SDRAM from newegg.com. Here's a link:
Also found out that now you can use the promo code CNETHELP1 to save $10 on any Rosewill product with a $20 minimum Rosewill product purchase. I think you can use the code multiple times, too, so you might want to place two separate orders if it's more cost effective.
I haven't had my G5 iMac long yet (less than a week), but the memory seems rock solid. Only issue so far is with the fan noise. From what I've read, I'm not the only one, either.